Plug-in electrical receptacle



June 9, 1953 w. P. KELLER 2,641,746

PLUG-I/N ELECTRICAL RECEPTACLE Filed June 28, 1949 2 Shanta-Sheet 1 Airolwrrs.

June 9, 1953" w. P. KELLER 2,641,745

' PLUG-IN ELECTRICAL REQEPTACLE meq June 28, 1949 2 Sheets-Sheet 2 11V VEN TOR By/ mw, fl

ATTORNEYS.

Patented June 9, 1953 UNITED STATES. PATENT OFFICE 2,641,746 y PLUG-IN ELECTRICAL RECEPTACLE Walter P. Keller, Chicago, 111. A

Application June 28, 1949", Serial No.'101,8 38 g I This invention relates to plug-in connectors; in particular, it concerns a greatly improved'receptacle adapted for co-operation with prongtype plugs. While the primary field of usefulness of such devices is as connectors in electrical circuits, their range of usefulness is not limited to such applications.

An object of the present invention is to provide a receptacle or socket for prong-type plugs which combines ease of manufacture with exceptional mechanical strength and stability.

Another object of the present invention is to provide a receptacle of the type described which is susceptible of extreme economy in manufacture, being formed, in a typical embodiment, of two molded pieces of insulating material and two readily formed metal parts.

I Still another object of the present invention is to provide a receptacle of the type described wherein complete freedom from relative movement of parts is assured without the necessity for any permanent connection, by riveting or otherwise, between the metal contact members and the structural parts normally formed of insulating material.

A, still further object of the present invention is to provide a receptacle of the type described wherein novel and simple, yet extraordinarily effective, means are provided for locking the metal contact members in their proper position within the structural members and for insuring against dislocation of such members asa result of forces transmitted by the prongs of the plugs with which the receptacle is used. I

A conspicuous disadvantage of prior-art receptacles of the type under consideration is that such receptacles required rivets for effective locking' of the metal contact members into the structural parts of the receptacle. This construction either made the receptacle dangerous by pro-" viding'a pair of electrically hot rivets in an accessible place on the back of the socket or it required that the rivets be set ina counter-sunk recess and protected from external access by sealing wax or other material. Either alterna tive was highly objectionabletheflrst because it was dangerous, and the second because it was time-consuming and expensive; Accordingly, one of the principal objects of this invention is to provide a receptacle wherein positive mechanical locking of the contact members against movement is accomplished without any exposure, on the external parts of the receptacle, of electrically hot conductors.

1 Other objects and advantages of my invention will apparas the specification proceeds.

4 Claims. (01. 339-191) 2 I have, in the accompanying drawing, illustrated two embodiments of my invention. Of the various figures of the drawing, Fig. 1 is a perspective view of one illustrative embodiment of my invention, shown in conjunction with a plugin fuse holder; Fig. 2 is aplan view of the embodiment of Fig. lshowing the manner in which it may be mounted on theforward wall of a terminal box; Fig. 3 is a side'sectional view of the receptacle of Fig. 1; Fig. 4 is an exploded sectional View similar to Fig. 3 with the parts separated to bring out clearly their coaction; Fig. 5 is a plan view ofthe base portion of the embodiment of Fig. 1, shown with the contact members in position but with the cover member removed; Fig. 6 is a bottom view of the cover'member of the embodiment of Fig. 1 as seen looking upward from the under side when the cover member is removed from the base member; Fig. 7 is a plan view of a second embodiment of my invention; Fig. 8 isa plan view of the embodiment of Fig. 7 as it appears. with the cover member removed but with'the contact members in place; Fig. 9 is a sectional view of the embodiment of Fig. 7, the section being taken along the lines 9-9 of Fig. '7; and Fig. 10 is an exploded sectional view similar to Fig.9 but with the parts separated to bring out the mannerin which they coact.

, The first embodiment of my invention, as shown in Figs. 1-6. comprises a base member ID, a cover member I], and a pair of metal contact members I 2 and l 3- respectively.

The embodiment of my invention shown in Figs; 1 6 isadapted for back-of-panel mounting in a terminal box l4. As shown in Fig. 2, the panel or forward wall'of the terminal box'in question; is provided, by stamping or otherwise, with an aperture adapted to receive'the forward faceof my receptacle. Since the embodiment shown is provided with a circular forward face, the aperture should be circular and equipped with apair of'inwardly extending ears, typified by ear Ila in Fig.2, for'facilitating rigid-mounting of my receptacle. ,The basemember ID and the cover member II are formed-for effecting a cooperative fit with one another, and are held together by a "pairof screws I6 Which pass through suitable apertures IT in cover member H. and screw into threaded apertures l8 in base member I0; When the receptacle i to be mounted in a terminal'box; the, screws 16 may be passed through apertured ears I la before entering cover member l I, and the assembly of my receptacle and its firm support on a terminal box may thus be accomplished in a single operation. To facili-. tate-"mounting of my receptacle and to. assure complete freedom from movement in response to torsional stresses, a pair of recesses I9, shaped to fit tightly with ears Ma, are provided in the forward face of cover member II.

Base member I9 and cover member I I of my receptacle will normally be formed entirely of insulating material and, in the normal, economical mode of manufacture, will be respectively molded from thermosetting plastic.

The forward face of cover member II is provided with a pair of slots 20 and 2 I, intended to receive the contact prongs 22 of the fuse holder 23 or other plug-in device being used with the receptacle. In the embodiment shown, slot 28 is somewhat shorter than slot 2| so as to permit use with a polarized plug to insure against inadvertent reversal of electrical connections through the receptacle. If the receptacle is intended for use in applications wherein polarity is of no significance, slots 20 and 2I may be made equal in length.

As may be seen best from Figs. 3 and 4, base member I is provided with a pair of symmetrically disposed recesses 24 and 25, formed as seats for metallic contactmembers I2 and I3. In the embodiment shown, contact members I2 and I3 include spring brush or rubbing members, denoted respectively 26 and 21, riveted, by rivets 28 and 29 respectively, to extension members 30 and BI. Extension members 30 and 3| consist of relatively heavy and rigid metal bars which underlie the spring members 26 and 21. The portion of members 3E! and 3| which are secured by the rivets to the bottom portion of the spring members are flat on both their upper and lower faces and are substantially coextensive with the bottom portion of the spring members along two sides thereof. Members 3!! and 3I respectively extend beyond the spring members on two sides, however, forming respectively side extensions 30a and 3Ic and terminal-carrying extensions 3% and SH).

To permit the under side of members 30 and 3 I to seat firmly on the bottoms of recesses 24 and 25, sub-recesses 24c and 25a may be provided to receive the rivets 28 and 29' respectively.

Terminal extensions 30b and 3Ib may be provided with apertures 32 to receive terminal screws 33. Electrical contact may be made to contact members I2 and I3 in the conventional manner by bending wires around screws 33 and securin them by tightly screwing screws 33 into apertures 32.

As may be seen by reference to Figs. 1, 3, and 4, the terminal extensions 30b and 3 lb emerge from base member I0 and project externally of the receptacle. Recesses 34 and 35 are provided in the outer rim of base member ID to permit terminal extensions 30?) and 3Ib respectively to emerge from base member ID in a position such that the upper surfaces of terminal extensions 30b and 3 lb are flush with the rim of base member III when contact members I2 and I3 are properly seated in recesses 24 and 25 respectively.

The cap or cover member II is formed generally for co-operation with base member I0, and its outer conformation should normally match that of base member I0. In the present example, both base member III and cover member II are formed in a generally cylindrical shape with a circular cross section. The height, or axial length, of cover member I I is chosen to provide a limited amount of clearance between the top of cover member II and the uppermost extension of contact members I2 and I3 when those members are properly seated in the base member. As may be seen from Figs. 1, 3, and 4, the lower rim of cover member II is formed to co-operate with and fit snugly to the rim of base member Ill.

Along its midline midway between slots and 2|, cover member II is provided with a ridge 01' brace member 36 which extends as a solid body from the top of cover member II to the plane of the outer rim thereof. Member 36 extends beyond the planejust mentioned, but in its extension it is bifurcated to form-a pair of projecting feet 31 and 38. In the embodiment shown, feet 3'! and 38 are parallel to one another and are separated. by a distance substantially equal to the thickness of the wall separating recess 24 from recess 25. The length of foot members 31 and 38 is equal to the axial distance between the rim of base member ID and the upper surface of members 3B and 3| when they are seated in recesses 24 and respectively.

In the assembly of the embodiment of my invention shown in Figs. 1-6, the contactmembers l2 and I3 are first seated in recesses 24 and 25. This results in the under portions of members 39 and 3| resting securely on the bottoms of recesses 24. and 25 respectively, the over-all length of such bottom portions being substantially equal to the length of recesses 24 and 25. When such seating has been accomplished, terminal extensions b and 3Ib are seated in recesses 34 and with their upper surfaces flush with the rim of' base member II). Similarly, side extensions 30a and 3Ia occupy the innermost portions of, recesses 2E and 25 respectively. The cover member II is then placed over base member III and. pressed into firm engagement therewith. This causes feet 31 and 38 to engage and press upon side extensions 36c and. 3m respectively, andat the same time the outer rim of cover member II. is in engagement with and pressing upon the upper surfaces of terminal extensions 39b and 3 I 2). screws I 6 may then be inserted and screwed into threaded apertures l8 to complete the assembly of my receptacle. It is to be noted that the novel construction of my receptacle provides absoluteanchorage of contact members I2 and I3 against movement, regardless of the magnitude.

or direction of forces which, may be applied to the spring members 26 and 21 by the prongs 22 of a plug being inserted in the receptacle. Similarly, no matter how. tightly prong members 22 may be held by spring members 26. and 21, the

forcibleremoval of the prongs 22 cannot cause any shift in the position of contact members I2 and I3.

In Figs. 7-10inclusive, I have shown a second embodiment of my invention which, while it embodies the same basic novel conception as the.

, first embodiment, is adapted to somewhat different applications. The receptacle shown in Figs. 1-6 is of a type likely to be employed in relatively high-power electrical installations in factories and other industrial buildings. The wirin in nearly all such structures is carried in conduits and terminated in terminal boxes. Hence the construction of the Fig. l embodiment, with its externally projecting terminal extensions 3% and buildings electrical extensions are very frequently installed by running open wiring along the baseboards or mouldings; frequently a receptacle is inserted and the line continued beyond that receptacle to one or more other receptacles. I have provided, and have shown in Figs. 7-10, a

receptacle for such application which is entirely noted 5| and a pair of contact members, de-' noted generally 52 and 53 respectively.

As with the'other embodiment ofmy invention shown and described, the cover member 5| is provided with a pair of slots 54 to afford a means of access of the prongs of a plug to the contact members 52 and 53. Since polarized connection is normally not necessary in applications of the sort for which the Fig. 7 embodiment is designed, the slots 54 are shown as being of the same width. It will of course be understood that, just as with the Fig. 1 embodiment, the slots may be polarized'or not as preferred.

The cover member 5| is suitably apertured to receive screws 55 which serve to lock together the cover and base members 5| and 50 respectively. Screw 55 pass through apertures 56 in base member 56. If desired, screws 55 may be machine screws, in which case the apertures 56 may be suitably threaded to receive them. This type of construction is desirable for extension cords and other applications wherein firm anchorage of the receptacle to a Wall is'not called for. If the receptacle is to be anchored to a wooden moulding, baseboard, or floor, screws 55 may be of the tapered wood-screw variety and apertures 56 may be made large enough to clear their shanks. In such a case, the screws 55 can perform the double function of anchoring the respective structural parts of the receptacle together and at the same time anchoring the same to the baseboard or other fixed object.

The contact members 52 and 53 comprise respectively spring members 5'! and 58 and base members 59 and 69, anchored together respectively by rivets 6|.

The base members 59 and 66 are somewhat wider than spring members 51 and 58 so as to provide side extensions 59a and 60a alongside each of the spring members 51 and 58. Moreover, the base members 59 and 60 are extended in length a short distance beyond the ends of spring members 51 and 58 so as to provide connector terminal surfaces 59b and 601). Each of the connector terminal surfaces59b and 60b is provided with a threaded aperture to receive a terminal screw 62.

Base member so is provided with a pair of parallel recesses 63 and 64, said recesses being disposed symmetrically with respect to the midline of base member 50. The recesses 63 and 64 are shaped to receive contact members 52 and 53; sub-recesses 63a and 64a in the bottoms, respectively, of recesses 63 and 64 accommodate the downwardly projecting portions of rivets 6| and terminal screws 62. The width of recesses 63 and 64 is substantially equal to the width of base members 59 and 66 of contact members 52 and 53. A pair of small recesses 65 are provided in the upper rim of base member 50 to permit electric cords to pass into the receptacle for terminal connections to screws 62.

The cover member 5| of this embodiment of my invention is hollow, like the cover member of the Fig. 1 embodiment. Its outer wall is cylindrical in shape, to register and co-operate with the cylindrical base member 59. The axial distance from the top of cover member 5| .to the lower rim thereof is adjusted to providea limited clearance between the top of member 51 and the uppermost portionsof spring members 51 and 5,8.

A pair of downwardly-extending feet 66 and 61 constitute an integral extension of the side wall of cover member 5|;feet 66 and 61 are A midline ridge or brace member'68 extendsdownward along the midline of cover member 5| from the underside of the top thereof; it

continues downwardly as a solid member to the point flush with the rim of member 5| ;;therebelow the member 68 is bifurcated to form a pair of feet 69 and 16, separated one from another by a distance substantially equal to the thickness of the wall separating recess 63 from recess 64. The length of feet 69 and I6 is, in the embodiment shown, equal to that of feet 66 and 61. V p

In the assembly of the embodiment of my invention shown in Figs; 7-10, the contact members 52 and 53 are first securely seated in recesses 63 and 64. Wires maybe connected to terminal screws 62 either before or after the seating of terminal screws 62 and contact surfaces 59b are provided on opposite sides of contact members 52 and 53, wiring may be carried "straight through if desired, one cord coming in through one of the recesses 65 and the other cord departing through the other recess 65, as shown in Figs. '7 and 8.

After the contact members have been seated in the recesses 63 and 64, the cover member 5| is seated over base member 56. This results in a snug matching fit between the respective rims of members 56 and 5|, while at the same time feet 66, 61, 69, and 10jcome firmly into contact with and press upon the side extension surfaces 59a and 60a of the contact members 52 and 53. Thus the contact members are firmly anchored against movement when the cover member is in place, just as with the embodiment of my invention shown in Figs. 1-6. After the cover member 5| is in place, screws 55 may be inserted and the receptacle is thereupon ready for use. Completely dependable anchorage of the contact members 52 and 53 is thus accomplished, and no electrically hot conductors are manually accessible from the outside of the receptacle. Thus the novel construction of my receptacle sets new standards both of safety, mechanical strength, simplicity, and economy ofmanufacture.

While I have in this specification described in considerable detail two embodiments of my inseems of my nven i be n tlfmiied to the specific.

embodiments illus eetedbiltthat it begdete mined solely with reierencato the appended claims,

lel im ,A re epta e or a prene-tr ep us Gemprisinga base member provided witha recess, a spr ng on ct membe ada ed t receive in s r a ement p nsip s d p us... s cont ct memb r being :i med f r ry in. saidrecess and'being provided with a pair of side ert ien ue dr eeee i r e o po te ides i's t ct memb r and a e r membercem risi a s et posi ioned over th recess to admit. the p ne e -eng e ent with th an fleet. member and being provided also witha foo adapt d o enter the rece lonssidethe cam tect m b r, sa d. s ri g contact member bei other side. extension b.eing locked in said last-j men i ned. recess nd secur d against movement. by being clamped between the rim of the cover member and the bottom .of said recess. I

3. A receptacle for a prong-type plug comprising. a first structural m mber p e with a pair of rece ses, a spr ontactm mber o ea eess'aidapted tcrec iie. sp e In nt one of the prongspf said plug, each of said contact members being respectively formed for entry in saidrecesses andbeing provided with a p ir efsidei extensions. respectively situated on QPPQsite sides of the contact member, and a second s ral member form d o fit .0-.opera ively on. the first structural ber, d. ne struc ural me b r being, provid d with feet adantedto-enter he; resp e e nd to press on ere of theside exte sions of each e tact mem r o. l k he same n o i ion b tween said feet andsaid first structural mem her, one of said structural members having also.

a pair of rim recesses for accommodation of the otherpairof side extensions, said second side extensions being received in said recesses and locked against movement by being clamped between the'two structural members. 1

4. A receptacle for a prong-type plug comprising a base memberprovided with a pair of recesses oriented side by side in bilaterally symmetrical position and separated one from another .by a wall extending along; the midline of said base member, a spring contact member for 1 recess dapted to receive in spring en agement oneof the prongs of said plug, each of saidcentact members being respectively formed for entry in said recesses and being provided with a side extension in surface contact with the base member when said contact members are situated in. said respective recesses, and a cover member formed for co-operative fit on; the base member,

said cover member comprising slots positioned over said recesses to admit said prongs to em gagement With those respective contacts and be! ing provided also with a midline ridge member bifurcated at its lower extremity to straddle said midline Wall of the base member and to provide thereby a pair of feet adapted to enter the respective recesses and to press on said side extensions for clamping the same in position against movement When the cover member and thebase member are fitted together.

WALTER P. KELLER.

References Cited in thefile of this patent UNITED STATES PATENTS 

